Expect more bird flu viruses to jump to humans, warns health official in China

The lead World Health Organization official in China expects more bird flu viruses to jump to humans in the country after two new strains, H7N9 and H10N8, emerged fewer than 12 months apart.

“We do expect to see more such strains pop up,” said Bernhard Schwartlander, the Beijing-based WHO China representative. Bird flu cases have tended to carry unusually high fatality rates, and the prospect of a novel strain taking root in human populations, and possibly jumping between people, is a continued source of anxiety for those monitoring global public health.

“We are nervous, because we know that things can change, and that may cause big problems,” said Dr. Schwartlander in an interview Wednesday. “We need to be very careful and be on alert. That’s very clear.”

The discovery of H10N8, which killed a 73-year-old Chinese woman in December and sickened another, marks the fifth strain of avian influenza to jump from birds to humans in 17 years. It comes after H7N9 was discovered last February. That virus has since killed at least 70 world-wide.

On Tuesday, Chinese researchers reported in the Lancet that the H10N8 shares much of its genetic base with H5N1, the bird flu strain that emerged in 2009 that has killed some 386 people, including an Alberta woman who died Jan. 3, in the first North American death. A genetic mutation allows H10N8 to better adapt to mammals, making it a particular cause for concern.

And researchers have already identified other potentially dangerous viruses lurking in the shadows. Last August, scientists working with the H7N7 virus, which already exists in the Chinese poultry population, said it too was capable of jumping to mammals in lab tests. If it continues to circulate, “I am sure that human infection cases will occur,” University of Hong Kong researcher Guan Yi said then.

Still, health officials have found no evidence of sustained human-to-human bird flu transmissions, including over the ongoing Chinese lunar new year season, when the risk of such transmission is particularly high as hundreds of millions of people jam into trains, buses and cars to visit home.

“That’s the good news. The bad news, of course, is that may change, and that’s in the nature of the virus,” said Dr. Schwartlander. “The influenza virus has the ability to shift, to change over time.”

The lead World Health Organization official in China expects more bird flu viruses to jump to humans in the country after two new strains, H7N9 and H10N8, emerged fewer than 12 months apart.

“We do expect to see more such strains pop up,” said Bernhard Schwartlander, the Beijing-based WHO China representative. Bird flu cases have tended to carry unusually high fatality rates, and the prospect of a novel strain taking root in human populations, and possibly jumping between people, is a continued source of anxiety for those monitoring global public health.

“We are nervous, because we know that things can change, and that may cause big problems,” said Dr. Schwartlander in an interview Wednesday. “We need to be very careful and be on alert. That’s very clear.”

The discovery of H10N8, which killed a 73-year-old Chinese woman in December and sickened another, marks the fifth strain of avian influenza to jump from birds to humans in 17 years. It comes after H7N9 was discovered last February. That virus has since killed at least 70 world-wide.

On Tuesday, Chinese researchers reported in the Lancet that the H10N8 shares much of its genetic base with H5N1, the bird flu strain that emerged in 2009 that has killed some 386 people, including an Alberta woman who died Jan. 3, in the first North American death. A genetic mutation allows H10N8 to better adapt to mammals, making it a particular cause for concern.

And researchers have already identified other potentially dangerous viruses lurking in the shadows. Last August, scientists working with the H7N7 virus, which already exists in the Chinese poultry population, said it too was capable of jumping to mammals in lab tests. If it continues to circulate, “I am sure that human infection cases will occur,” University of Hong Kong researcher Guan Yi said then.

Still, health officials have found no evidence of sustained human-to-human bird flu transmissions, including over the ongoing Chinese lunar new year season, when the risk of such transmission is particularly high as hundreds of millions of people jam into trains, buses and cars to visit home.

“That’s the good news. The bad news, of course, is that may change, and that’s in the nature of the virus,” said Dr. Schwartlander. “The influenza virus has the ability to shift, to change over time.”